Up to now, a disc cartridge has been in use which holds a flexible magnetic disc as a disc used as a recording medium for information signals. This flexible magnetic disc is hereinafter referred to as a magnetic disc.
As a disc cartridge holding a magnetic disc, a first disc cartridge holding a magnetic disc having a recording capacity of 1 megabyte (MB) and a second disc cartridge holding a magnetic disc having a recording capacity of 2 megabyte (MB) are currently in use. The second disc cartridge, housing the 2 MB magnetic disc, is standardized as MF2HD.
These first and second disc cartridges have the thickness, outer size and the structure of a shutter used for opening/closing an recording and/or reproducing aperture formed in a main cartridge body portion in common for enabling the use of a common disc drive device interchangeably.
A first disc cartridge 1, holding a magnetic disc of a recording capacity of 1 MB, and a second disc cartridge 2, holding a magnetic disc of a recording capacity of 2 MB, are each provided with a main cartridge body portion 5 and a magnetic disc 6 with a diameter of 3.5 inch rotatably housed in the main cartridge body portion 5, as shown in FIGS. 1 to 4. The main cartridge body portion 5 is made up of a rectangular-shaped upper cartridge half 3 and a rectangular-shaped lower cartridge half 4 abutted and connected to each other.
The magnetic disc 6, held in the main cartridge body portion 5, is fitted with a center hub 7 formed as a magnetic metal plate and which is adapted for being clamped to a disc table of a disc rotating/driving unit provided on a disc driving device. This hub 7 is exposed to outside via a center aperture 8 bored in the lower cartridge half 4 of the main cartridge body portion 5.
The outer four sides of the rectangular-shaped main cartridge body portion 5 are constituted by a front wall section 9, a back side wall section 10 and left and right sidewall sections 11, 12. The front wall section 9 serves as the inserting side end of the main cartridge body portion 5 into the disc driving device as indicated by arrow A in FIGS. 1 to 4. The back side wall section 10 is the side lying opposite to the front wall section 9 and which operates as an ejection leading end when ejecting the main cartridge body portion 5. In a corner on the front wall section 9 of the main cartridge body portion 5 is formed a mistaken insertion inhibiting unit 13 operating as an inclined surface for preventing mistaken insertion of the disc cartridge into the disc driving device.
The upper and lower surfaces of the main cartridge body portion 5, provided by the upper and lower cartridge halves 3 and 4, are formed with rectangular-shaped recording and/or reproducing apertures 14 and 15, at mid portions thereof in the left-and-right direction, for exposing a portion of a signal recording area of the magnetic disc 6 held in the main cartridge body portion 5 to outside across the inner and outer rims of the magnetic disc 6.
On the main cartridge body portion 5 is movable mounted a shutter member 17 adapted for opening/closing recording and/or reproducing apertures 14, 15 provided in the main cartridge body portion 5. The shutter member 17 is U-shaped in cross-section section and is fitted on the front wall section 9 of the main cartridge body portion 5 for overlying the recording and/or reproducing apertures 14, 15 formed in the main cartridge body portion 5. The shutter member 17 is biased by a torsion coil spring, not shown, provided in the main cartridge body portion 5, into movement in a direction of closing the recording and/or reproducing apertures 14, 15 as indicated by arrow D in FIGS. 1 to 4.
The main cartridge body portion 5 is also provided with a shutter movement recess 18, defining a movement area for the shutter member 17, for extending from the upper and lower sides to the front wall section 9. The main cartridge body portion 5 is also provided with a label bonding recess 19 extending from a mid portion on the upper surface to the back side wall section 10 and thence to the lower surface of the main cartridge body portion 5.
In both corner areas on the lower surface of the main cartridge body portion 5 surrounded by the front wall section 9, both sidewall sections 11, 12 and the outer rim of the magnetic disc 6 housed in the main cartridge body portion 5, in the inserting side into the disc drive device, and in both corner portions on the lower surface of the main cartridge body portion 5 surrounded by the back wall section 10, both sidewall sections 11, 12 and the outer rim of the magnetic disc 6 housed in the main cartridge body portion 5, on the ejecting side from the disc drive device, there are formed height reference planes 21, 22, first and second positioning reference holes 23, 24 and a mistaken recording inhibiting unit 26, as shown in FIGS. 2 and 4. The height reference planes 21, 22 serve for setting the mounting height level when the first or second disc cartridge 1 or 2 is loaded on the disc drive device. The first and second positioning reference holes 23, 24 are engaged by positioning pins provided on the disc drive device for setting the horizontal mounting position.
The lower side of the second disc cartridge 2 is also formed with a first capacity discrimination hole 27 in the opposite side corner towards the back side wall section 10 for specifying that the magnetic disc 6 with the recording capacity of 2 MB has been housed therein, as shown in FIG. 4.
Further, in the left and right sidewall sections, 11, 12 towards the front wall section 9 of the main cartridge body portion 5, there are formed engagement recesses 25, 25 engaged by engagement portions of a loading mechanism for the disc cartridge provided on the disc drive device, as shown in FIGS. 2 and 4.
Specifically, in the four corner portions on the lower surface of the main cartridge body portion 5, there are formed four left and right paired height reference planes 21, 22 so as to clear the shutter movement recess 18 and the label bonding recess 19. Within the left and right paired height reference planes 21, 22 towards the front wall section 9 of the main cartridge body portion 5 are symmetrically formed first and second positioning reference holes 23, 24 in the left-and-right direction. The first positioning reference hole 23 is of a true circular shape, while the second positioning reference hole 24 is of an elliptical shape having the direction perpendicular to the inserting direction of the first and second disc cartridges 1, 2 into the disc drive device as its long axis.
The engagement recesses 25, 25 are formed to a semicircular profile in corner portions towards the front wall section 9 of the main cartridge body portion 5 with left-and-right position symmetry, as shown in FIGS. 2 and 4. These engagement recesses 25, 25 are provided between the front wall section 9 and the left and right paired positioning reference holes 23, 24 of the main cartridge body portion 5 and are formed for extending from the lower surface to the sidewall sections, 11, 12 of the main cartridge body portion 5.
The mistaken recording inhibiting unit 26 is provided between the back side wall section 10 and the height reference plane 22 of the main cartridge body portion 5, and includes a recording inhibition discriminating hole 26a and a mistaken recording inhibiting member 26b. The recording inhibition discriminating hole 26a is passed through the upper and lower halves 3, 4 of the main cartridge body portion 5 and the mistaken recording inhibiting member 26b is movably assembled between the upper and lower halves 11, 12 for opening/closing the recording inhibition discriminating hole 26a.
The first disc cartridge 1, holding the magnetic disc 6 with the recording capacity of 1 MB, is not provided with a capacity discriminating portion for specifying the type of the magnetic disc 6 housed therein, as shown in FIGS. 1 and 2. Conversely, the second disc cartridge 2, holding the magnetic disc 6 with the recording capacity of 2 MB, is provided with the first capacity discrimination hole 27 specifying that the magnetic disc 6 with the recording capacity of 2 MB is housed therein, as shown in FIGS. 3 and 4. The first capacity discrimination hole 27 is provided at a corner towards the lateral surface 11 towards the back side wall section 10 of the main cartridge body portion 5, as shown in FIGS. 3 and 4. The first capacity discrimination hole 27 is formed as a rectangular-shaped through-hole traversing the upper and lower cartridge halves 3, 4 in left-and-right symmetry with respect to the recording inhibition discriminating hole 26a of the mistaken recording inhibiting unit 26.
A disc drive device 30, on which the above-described first and second disc cartridges 1, 2 are mounted selectively interchangeably, is comprised of a base block 32 of a metal plate arranged in a main body portion 31 and a cartridge loading unit 33 mounted on the base block. The first or second disc cartridge 1 or 2 is adapted to be loaded on the cartridge loading unit 33. The disc drive device 30 is also provided with a disc rotating/driving unit 34 at a mid portion of the cartridge loading unit 33. The disc rotating/driving unit 34 is adapted for rotationally driving the magnetic disc 6 housed within the first and second disc cartridges 1, 2. The disc rotating/driving unit 33 include a spindle motor 35 mounted on the base block 32 and a disc table 36 mounted as-one with a spindle shaft 35a of the spindle motor 35.
On the base block 32, there are provided supports 39, 40 adapted for supporting the height reference planes 21, 21 on the rim of the first and second positioning reference holes 23, 24 of the first or second disc cartridges, 1,2 loaded on the cartridge loading unit 33 and the height reference planes 22, 22 towards the back side wall section 10. These supports 39, 40 are arranged with left-and-right symmetry for surrounding the spindle motor 35 about the spindle shaft 35a as the center. These supports 39, 40 are formed by bosses by partially segmenting the base block 32 or by pins set upright on the base block 32.
Centrally of the supports 39, 39, supporting the height reference planes 21, 21 on the rim of the first and second positioning reference holes 23, 24 of the first or second disc cartridge 1 or 2 are set upright positioning pins 37, 38 engaged with the first and second positioning reference holes 23, 24 for setting the horizontal loading position of the first or second disc cartridge 1 or 2 with respect to the cartridge loading unit 33, as shown in FIG. 6. These positioning pins 37, 38 are tapered as shown in FIG. 6.
On the base block 32, there are arranged a cartridge loading detection switch 44 and a mistaken recording detection switch 45 on a cartridge inserting/detachment opening 43 on the front side of the main body portion 31 and towards a lateral side 31a of the main body portion 31 for detecting the loading of the first or second disc cartridge 1 or 2 on the cartridge loading unit 33. Towards the opposite side lateral wall section 31b is arranged a first capacity detection switch 46.
The mistaken recording detection switch 45 and the first capacity detection switch 46 are arranged with left-and-right symmetry on both sides of the spindle shaft 35a of the spindle motor 35, as shown in FIG. 5. Towards the first capacity detection switch 46 in proximity to the mistaken recording detection switch 45 is mounted a cartridge loading detection switch 44. The switches 44 to 46 are of the thrusting type and mounted on a printed circuit board 48 provided on the lower surface of the base block 32, as shown in FIG. 6. These switches 44 to 46 are provided with thrusting elements 44a, 45a, 46a, respectively, which are protruded towards the cartridge loading unit 33 provided on the upper surface of the base block 32 via an aperture 49 formed in the base block 32.
On an inner end of the printed circuit board 48 is provided a connection terminal 50 connected to a connection plug interconnecting the disc drive device and an external processing device, such as a computer, as shown in FIG. 5.
The first and second disc cartridges 1, 2 are loaded on the disc drive device 30, configured as described above, for recording and/or reproducing information signals on or from the magnetic disc 6 held in the main cartridge body portion 5.
The first or second disc cartridge 1 or 2 is inserted in a horizontal position into the main body portion 31 via cartridge inserting/detachment opening 43 in a direction indicated by arrow A in FIG. 5, with the front wall section 9 of the main cartridge body portion 5 carrying the shutter member 17 as the inserting end. When the first or second disc cartridge 1 or 2 is inserted into the main body portion 31, the shutter member 17 is moved in the direction indicated by arrow C in FIG. 5, by the cartridge loading unit provided in the main body portion 31, against the force of the torsion coil spring, for opening the recording and/or reproducing apertures 14, 15. When inserted as far as the position facing the cartridge loading unit 33, the first or second disc cartridge 1 or 2 is lowered towards the recording/reproducing position of recording and/or reproducing information signals on or from the magnetic disc 6, so that it has the height reference planes 21, 22 supported by the supports 39, 40, while having the positioning pins 37, 38 engaged in the first and second positioning reference holes 23, 24 so as to be loaded in correct height and horizontal positioning on the cartridge loading unit 33. At this time, the magnetic disc 6 held in the main cartridge body portion 5 has its hub 7 chucked on and rotated in unison with the disc table 36. Into the recording and/or reproducing apertures 16 in the upper and lower sides of the main cartridge body portion 5, opened as a result of movement of the shutter member 17, upper and lower paired magnetic heads, not shown, are intruded into contact with the upper and lower surfaces of the magnetic disc 6. As the magnetic disc 6 is run in rotation by the spindle motor 35, information signals are recorded or reproduced on or from the upper and lower sides of the magnetic disc 6 by the paired magnetic heads.
Turning to the disc drive device 30, when the first or second disc cartridge 1 or 2 is loaded on the cartridge loading unit 33, the thrusting elements 44a, 45a, 46a of the cartridge loading detection switch 44, mistaken recording detection switch 45 and the first capacity detection switch 46 are selectively actuated by the lower surface of the main cartridge body portion 5 in order to detect whether or not the disc cartridge 1 or 2 has been loaded, whether or not the information signals can be recorded on the magnetic disc 6 and which is the recording capacity of the magnetic disc 6 housed in the loaded disc cartridge 1 or 2. That is, if the recording inhibiting hole 26a of the mistaken recording inhibiting unit 26 is closed by the mistaken recording inhibiting member 26b, the thrusting element 45a is thrust by the mistaken recording inhibiting member 26b to turn on the mistaken recording detection switch 45, thus allowing to recognize the `recordable state` in which the information signals can be recorded on the magnetic disc 6. If the recording inhibition discriminating hole 26a is opened, the thrusting element 45a is not intruded into the recording inhibiting hole 26a without being thrust, with the mistaken recording detection switch 45 continuing to be turned off to allow to recognize the `recording inhibiting state` in which recording of information signals on the magnetic disc is inhibited. When the first disc cartridge 1 is loaded on the cartridge loading unit 33, the thrusting element 46a is thrust by the planar lower surface of the main cartridge body portion 5 to turn on the first capacity detection switch 46, thus allowing to recognize that there is loaded the first disc cartridge 1 holding the magnetic disc 6 with the recording capacity of 1 MB.
When the second disc cartridge 2 holding the magnetic disc 6 with the recording capacity of 2 MB is loaded on the disc drive device 30, the cartridge loading detection switch 44 and the mistaken recording detection switch 45 effect the same detection operation as that when the first disc cartridge 1 is loaded. However, the thrusting element 46a is intruded into the first capacity discrimination hole 27 without being thrust. The first capacity detection switch 46 continues to be turned off to allow to recognize the loading of the second disc cartridge 2 holding the magnetic disc 6 of the 2 MB recording capacity.
Thus, the first capacity detection switch 46 detects the possible presence of the first capacity discrimination holes 27 of the first and second disc cartridges 1, 2 for detecting the types of the loaded disc cartridges 1, 2.
Meanwhile, with a disc cartridge holding a flexible magnetic disc, the recording capacity is raised to, for example, not less than 100 MB. With the disc cartridge of this type which holds the magnetic disc of the increased recording capacity, it has been desired to use the disc cartridge in a disc drive device interchangeably in common with the above-mentioned first and second disc cartridges and simultaneously to enable distinguishment from the first and second disc cartridges 1, 2 and recognition of the recording capacity of the magnetic disc held in the main cartridge body portion.
For distinguishment of the disc cartridge holding a magnetic disc having an increased recording capacity of not less than 100 MB from the first disc cartridge 1 holding the 1 MB capacity magnetic disc 6 and the second disc cartridge 2 holding the 2 MB capacity magnetic disc 6, interchangeable with the disc cartridge holding the magnetic disc of the increased capacity, it may be contemplated to provide a second capacity distinguishing hole for distinguishing the increased capacity independently of the first capacity discrimination hole 27 provided in the second disc cartridge 2, and to detect the possible presence of the second capacity discriminating hole by a large capacity discriminating detection switch provided in the disc drive device in the same way as by the first capacity discrimination hole 27 provided in the second disc cartridge 2. However, in this case, special considerations need to be made as to the position of the second capacity discriminating hole.
Specifically, in the currently used disc drive device 30, selectively employing only the first and second disc cartridges 1, 2, there is provided a thrusting spring in the cartridge loading unit, as shown in FIG. 6. This thrusting spring thrusts the first and second disc cartridges 1, 2 loaded on the cartridge loading unit 33 towards the supports 39, 40 provided on the cartridge loading unit 33. The comprehensive pressing force F.sub.1 of the thrusting spring, pressing the main cartridge body portion 5 against the supports 39, 40 in their entirety, is usually 300 to 400 g, with the distributed pressing force acting on the four supports 39, 40 being of the order of one-fourth the comprehensive pressing force F.sub.1, or 90 to 100 g.
The thrusting force F.sub.3 of each of the thrusting elements 44a, 45a, 46a of the cartridge loading detection switch 44, mistaken recording detection switch 45 and the first capacity detection switch 46, provided on the disc drive device 30, is approximately 36 g. Therefore, if three or more thrusting type detection switches each having a thrusting element are provided in proximity to one another in the vicinity of one of the supports 40, for example, of the four supports 39, 40, the sum total of the thrusting forces F.sub.3 thrusting the thrusting elements of these three or more detection switches, that is an overall thrusting force F.sub.4, needs to exceed 108 g, thus exceeding the upper limit of the distributed pressing force F.sub.2 applied to the sole support 40. This leads to the cartridge floating phenomenon, in which the main cartridge body portion 5 is floated upward from the sole support 40 by the overall force F.sub.4 with which the thrusting elements of the detection switches act for displacing the main cartridge body portion 5 away from the cartridge loading unit 33 against the bias of the thrusting spring.
On the occurrence of such cartridge floating phenomenon, there results the failure in chucking the magnetic disc 6 with respect to the disc table 36 or in the rotational driving of the magnetic disc 6 by the spindle motor 6. Moreover, with the recent tendency to a reduced thickness of the disc drive device 30, the detection switches also tend to be reduced in size, with the result that the thrusting elements provided on the detection switches also tend to be reduced in movement strokes. If the floating phenomenon occurs from the cartridge loading unit 33 of the disc cartridge 1 or 2, it may be feared that detection of possible loading of the disc cartridge 1 or 2 on the cartridge loading unit 33 or of the possibility of recording of information signals on the magnetic disc 6, or discrimination of the types of the loaded disc cartridge, such as the recording capacity, cannot be achieved reliably.
The track width of the recording tracks for the information signals, formed on the magnetic disc having the recording capacity of not less than 100 MB, is much narrower than the track width of the recording track formed on the magnetic disc with the recording capacity of 1 MB or 2 MB. Thus, if the disc cartridge holding the magnetic disc of the increased capacity and narrow track width is erroneously loaded in a disc drive device exclusively employing the above-mentioned first and second disc cartridges holding the magnetic discs with the recording capacity of 1 or 2 MB, the risk is high that the information recorded on the magnetic disc of the increased capacity be erased by the magnetic head adapted for recording the information signals on the magnetic disc with the recording capacity of 1 or 2 MB.
It is therefore mandatory that, if a disc cartridge holding the magnetic disc of the increased capacity is erroneously loaded on a disc drive device dedicated to the first and second disc cartridges holding the magnetic discs of the recording capacity of 1 or 2 MB, the `non-recordable state` can be recognized at all times.